Impact of Hidden Nodes on On-Demand AP Wake-Up Exploiting WLAN Signals

Yuma ASADA  Hiroyuki YOMO  

IEICE TRANSACTIONS on Communications   Vol.E99-B   No.4   pp.939-950
Publication Date: 2016/04/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2015EBP3311
Type of Manuscript: PAPER
Category: Terrestrial Wireless Communication/Broadcasting Technologies
green networking,  wireless LAN,  IEEE 802.11,  wake-up receiver,  hidden node,  

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This paper investigates the impact of hidden nodes (HNs) on on-demand access point (AP) wake-up that is employed to realize energy-efficient wireless LANs (WLANs). The considered wake-up signaling exploits IEEE 802.11 signals transmitted by a WLAN station (STA) to remotely activate a sleeping AP: a STA with communication demands transmits a series of WLAN frames with their length corresponding to the wake-up ID. A wake-up receiver attached to each AP detects the length of WLAN frames with the low-power operations of envelope detection and on-off-keying (OOK) demodulation. Since WLAN frames constituting a wake-up signal are transmitted by a STA following carrier sense multiple access (CSMA) protocol, they are vulnerable to the well-known hidden node (HN) problem. The impact of HNs on wake-up signaling is different from that on data communications since the wake-up receiver employs unconventional frame length detection to extract the information on the wake-up ID from the received signal. In this paper, we first investigate the impact of HNs on wake-up failure probability with theoretical and experimental evaluations. If the degradation of wake-up signalling due to HNs is observed for a STA, the corresponding STA may suffer from collisions due to the same HNs for its data communications even if it manages to succeed in the wake-up process. In this case, the wake-up operation itself may not be necessary. Therefore, we also compare the impact of HNs on wake-up signaling and that on data communications after the wake-up process. These results and discussions provide us with an insight on the impact of HNs on on-demand AP wake-up exploiting WLAN signals.